[pulseaudio-discuss] [PATCH]: High-definition audio pass-through support

Colin Guthrie gmane at colin.guthr.ie
Fri Nov 18 09:16:13 PST 2011

'Twas brillig, and Kelly Anderson at 18/11/11 16:37 did gyre and gimble:
> On 11/17/2011 11:41 PM, Maarten Bosmans wrote:
>> 2011/11/17 Kelly Anderson<kelly at silka.with-linux.com>:
>>> Hi,
>>> So I patched PulseAudio 1.1 for hdmi-surround-71 and lo and behold it
>>> worked.
>>> Here's a patch, hopefully we can get this added in the next official
>>> release
>>> of PulseAudio.  I know that there are quite a few Xbmc users that
>>> have been
>>> anxiously
>>> waiting for high-definition audio pass-through to work correctly.  Of
>>> course
>>> if someone
>>> has a better solution, that would be fine too.
>> Note that there's nothing inherently high-definition about the audio
>> data through a hdmi connector.
> True.  I should have said DTS-HD.  DTS-HD requires more bandwidth then 2
> channels @192K
> can handle.  8 channels @192K provides enough bandwidth (768K) to handle
> the high
> def audio formats such as DTS-HD.
>> How about also adding 4.0 and 5.1? That seems more complete.
> They weren't necessary for the pass-through support, although they may
> be beneficial
> for non-pass-through audio.

I'm confused.....

This isn't pass through is it? I mean it's defining an 8 channel PCM
device. You do not pass it encoded DTS, AC3 etc. etc. data, but an 8
channel PCM stream.

Pass through is quite different, but is also supported in PA 1.1
(provide the client application uses the new API to enable pass through).

Isn't this just enabling 7.1 channel output, such that the application
in question does the decoding and passes the PCM stream to your receiver

This isn't necessarily a bad thing to support, but I think the commit
message and such is then quite wrong (and judging from your comments,
perhaps your understanding of what is going on too might be quite off



Colin Guthrie

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